Siman - Shabbos Daf 17
- Movable items transmitting tumah as an ohel
The Rabbis enacted that any moveable item that has the thickness of an ox goad (approximately one third of a tefach wide/one tefach circumference) can serve as an ohel, transmit tumah and render the person an av hatumah.
R’ Akiva explains the reason for the prohibition was as follows. Midoraya, a farmer carrying a goad over a grave becomes a rishon through direct contact with the goad. Since he might mistakenly believe that the cause of his tumah status was the goad serving as an ohel, instead of his direct contact with it, he might conclude that an ohel in general only makes someone a rishon and only requires a day-long tumah, instead of the seven day purification.
The Rabbis therefore decreed that any moveable object that has a one tefach circumference which touches a person while serving as an ohel, renders the person an av hatumah.
- Replanting tamei terumah
Another one of the eighteen enactments was a decree regarding replanted terumah.
Midoraysa, when terumah is replanted, the resultant growth has the status of chullin and may be eaten by non-Kohanim, once the standard separations of terumos and maasros have been done.
The Rabbis were concerned that a Kohen in possession of tamei terumah, would intend to replant it in the sowing season so the new growth would be deemed tahor, and inadvertently come to eat that tamei terumah in the meantime.
They therefore enacted that the produce that results from replanted terumah has the same status as the original terumah. If the terumah was tahor, the produce was tahor and if the terumah was tamei then the produce was tamei. Therefore there would be no point for a Kohen to replant his tamei terumah.
- Bread, oil, wine and daughters of idolaters
The bread, oil, wine and the daughters of idolaters were prohibited as one of the eighteen enactments.
Prohibiting eating their bread and oil was a way to reduce socializing and prevent intermarriage. According to some, the prohibition of bread only applies to bread cooked in a private home, not commercial bread.
In addition to prohibiting drinking their wine, the Rabbis also forbid getting any benefit from it as a concern of יין נסך, wine poured as a libation to idols.
While marrying non-Jewish women is prohibited from the Torah, the Rabbis decree prohibited
yichud (seclusion) with them.
